The present invention is generally directed to apparatuses and methods for fabricating integrated circuit (IC) sensors and, more specifically, to an apparatus and method for attaching an IC sensor to a substrate.
Many integrated circuit (IC) devices do not encapsulate the entire IC chip in a protective package. For example, an IC sensor chip used in a fingerprint reader is a touch chip device that uses a sensor array to read a finger print. In order to work properly, the sensor array must be at least partially exposed in order to receive the finger of a user.
For these types of devices, it is necessary to package the IC sensor chip in such a way that the edges and wires of the IC sensor chip are protected, but the sensor array remains completely exposed. The packaging is usually accomplished using some kind of molding process. However, this process is made more difficult by the need to prevent molding flash from forming on the IC sensor and by the need to compensate for variation in die thickness and die tilt. The exposed IC sensor is brittle and must be handled carefully to prevent it from shattering.
Therefore, there is a need in the art for improved processes for fabricating integrated circuit packages that contain an at least partially exposed integrated circuit sensor.
To address the above-discussed deficiencies of the prior art, it is a primary object of the present invention to provide a method of fabricating an integrated circuit sensor package. According to an advantageous embodiment of the present invention, the method comprises the steps of: 1) mounting a substrate on a first mold block, the substrate comprising a substantially planar material having a first substrate surface on a first side and a second substrate surface on an opposing second side, such that the second substrate surface contacts a mounting surface of the first mold block; 2) placing an adhesive on the first substrate surface; 3) placing an integrated circuit sensor on the adhesive; and 4) pressing a second mold block against the first substrate surface, the second mold block comprising a cavity portion for receiving the integrated circuit sensor, a contact surface surrounding the cavity portion, and a compliant layer mounted with the cavity portion, wherein pressing the second mold block against the first substrate surface causes the contact surface to form with the first substrate surface a seal surrounding the integrated circuit sensor and further causes the compliant layer to press against a sensor array surface of the integrated circuit sensor, thereby pressing the integrated circuit sensor into the adhesive and the first substrate surface.
According to one embodiment of the present invention, the method further comprises the step of 5) injecting an encapsulant material into the cavity portion of the second mold block.
According to another embodiment of the present invention, the compliant layer forms a seal with the sensor array surface of the integrated circuit sensor, thereby preventing the encapsulant material from contacting the sensor array surface.
According to still another embodiment of the present invention, the method further comprises the steps of: 6) allowing sufficient time for the adhesive and the encapsulant material to set, thereby fixing the integrated circuit sensor to the first substrate surface and forming a protective package that encapsulates the integrated circuit sensor while leaving the sensor array surface exposed; and 7) removing the first and second mold blocks.
According to yet another embodiment of the present invention, the method further comprises the step of 8) pressing a clamping block associated with the first mold block against a portion of the second substrate surface opposite a position of the integrated circuit sensor on the first substrate surface.
According to a further embodiment of the present invention, the step of pressing the clamping block against the portion of the second substrate surface causes the first substrate surface to press against the integrated circuit and the adhesive, thereby pressing the sensor array surface of the integrated circuit sensor more tightly against the compliant layer.
The foregoing has outlined rather broadly the features and technical advantages of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features and advantages of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they may readily use the conception and the specific embodiment disclosed as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form.
Before undertaking the DETAILED DESCRIPTION OF THE INVENTION below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms xe2x80x9cincludexe2x80x9d and xe2x80x9ccomprise,xe2x80x9d as well as derivatives thereof, mean inclusion without limitation; the term xe2x80x9cor,xe2x80x9d is inclusive, meaning and/or; the phrases xe2x80x9cassociated withxe2x80x9d and xe2x80x9cassociated therewith,xe2x80x9d as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and the term xe2x80x9ccontrollerxe2x80x9d means any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, firmware or software, or some combination of at least two of the same. In particular, a controller may comprise a data processor and an associated memory that stores instructions that may be executed by the data processor. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.